WO2012154132A2

WO2012154132A2 - Adhesive/sealant preferably used for construction panels

Info

Publication number: WO2012154132A2
Application number: PCT/SI2012/000028
Authority: WO
Inventors: Mojca Japelj FIR; Bojan BRATUŽ; Aleš KRALJ; Ada BEGUŠ
Original assignee: Cbs Inśtitut, Celovite Gradbene Reśitve, D.O.O.; Tkk Proizvodnja Kemičnih Izdelkov Srpenica Ob Soči D.D.
Priority date: 2011-05-09
Filing date: 2012-05-04
Publication date: 2012-11-15
Also published as: EP2707444A2; WO2012154132A4; WO2012154132A3; SI23731A

Abstract

Adhesive/sealant with lower thermal conductivity used for insulated glass units (IGUs) and gas filled insulation construction panels (GFPs), said adhesive/sealant comprising hollow mineral and/or organic microspheres in its structure. The thermal conductivity of the adhesive/sealant is less than 0.30 W/mK, preferably less than 0.25 W/mK. Chemical and mechanical properties of such adhesive/sealant mass are comparable to existing sealants used for IGUs and GFPs.

Description

Adhesive/sealant preferably used for construction panels

Proposed technical field of invention

Thermal insulation, construction panels, adhesives/sealants,

ECLA: C08J3/20H, E06B3/56, C09K3/10D8, C09K3/10F

Technical problem

Technical problem to be solved by proposed invention is development of novel adhesive/sealant with lower heat conductivity for insulated glass units and gas filled insulation construction panels. Adhesive/sealant according to this invention has at least equal chemical and mechanical properties as comparable materials known in state of the art, however with lower conductivity which does not exceed 0.30 W/m .

State of the art

Construction panel is insulated glass unit (IGU) or gas filled insulation construction panel (GFP) comprised of one or more chambers to be used in building envelopes - integrated facades or curtain walls and windows. It should be sealed with adhesive/sealant. Adhesives/sealants are most often in forms of putties. Adhesive/sealant are well known in the area of IGUs or GFPs used for fixing of metal frame between two boards and prevention of gas leak from insulation core. The thermal resistance of these IGUs or GFPs is very important for reduction of energy consumption. One of prevalent development direction was reduction of thermal conductivity of metal frame or spacer using hybrid (metal-plastic) materials. To-day these spacers approach technical limit for low heat transfer therefore the heat transfer of the adhesive/sealant may already be higher than that of the spacers. The thermal conductivity of adhesive/sealant as known in state of the art is between 0.35 to 0.40 mW/k.

In state of the art the requirements for adhesive/sealant of IGUs and GFPs are well known, and they are:

• adhesive with cohesive fracture on glass, aluminium, stainless steel, tensile strength between 0.6 to 1.2 MPa (SIST EN 28339)

• hardness between 30 to 60 Shore A (ISO 868)

• elongation at break at least 50% (SIST EN 28339)

• resistance to flow is 0 mm (SIST EN 27390)

• test of constant load: tensile strength 0.30 MPa for 10 minutes (SIST EN 1279-6; used only for those with CE production mark)

State of the art shows three groups of relevant patents. The first group shows sealants based on polymers such as polysulfides, polymercaptans, silicones, polyurethanes, and their use in construction specifically as secondary sealant for IGUs or GFPs used for use in building envelopes - integrated facades or curtain walls or windows: US2543844, US2589151 , US4153594, US3689450, US6919397, CA2085077, EP1044936, US5430192, EP0097005, and EP0010888. Most often sealants based on liquid polysulfide polymer, chosen plasticizer and adhesion promoter usually from group of silanes is used today for these purposes. Polysulfid mixture is then hardened using hardener such as manganese dioxide. With addition of copolymers to the polysulfide mixtures on basis of epoxy, polythioether, polyurethane, polymercaptan etc. the mechanical properties are enhanced as well as gas and water vapor tightness of final sealant. The second group represents sealing materials decreasing their density by use of hollow microspheres into their structure: US4582756, US6915987, and US7067612. The same group includes patents in which the sealing masses are used which by inclusion of hollow microspheres into their structure achieve lower density and better mechanical properties such as tear strength, tensile strength, higher elasticity, resistance to fuels: US20040097643, WO2010019561, and US5663219. In particular patent US20040097643, describes preparation of sealing masses with lower density (from 0.7 to 1.3 g/cm ) having improved tensile strength. For achieving lower density of the sealant use of full and hollow fillers are proposed with lower density than basic sealing material. Full and hollow fillers can be mineral (ceramic, glass), or organic. It should be noted that by using these fillers in polymer sealing mass higher mechanical properties were achieved (tear and tensile strength) this being in contrast with established practice which has held: higher the tensile strength, lower the tear strength. This invention undermined old correlation, the authors citing introduction of proper fillers. Hardened or non-hardened sealing mass with lower density is appropriate for use in different areas: aerospace industry, transport industry (trains, ships, and vehicles), mechanical engineering, construction, civil engineering - anywhere where reduction of mass is important. However, this mass was not tested for use in the area of IGUs and GFPs. As such the authors did not involve themselves into questions whether their sealing masses reduce gas permeation (water vapor, argon) which is of key importance in the area of IGUs and GFPs. Their description does not show ability to provide for desired thermal conductivity of sealing masses as their product was not foreseen in energy efficient buildings.

The third group show one patent, namely US7569626, describing use of hollow or gas filled glass or ceramic microspheres for achieving lower thermal conductivity of biocompatible polymer used in medical therapies showing overheating due to electric power conduction. The patent does not mention thermal conductivity of polymer however, thermal conductivity of filler is mentioned, said thermal conductivity lower than 5 W/mK, preferably less than 2 W/mK. Said patent is in view of technical field of this invention a distant prior art as it is limited to biocompatible polymers for use in medicine. The research resulting in this patent the polymer adhesive/sealant with lower thermal conductivity for use in construction was developed, said field requiring specific technical and mechanical properties. Cited patent does not give information if described polymer mass provides for key technical requirements to be used as secondary sealant for IGUs and GFPs such as: tensile strength > 0.6 MPa, elongation at break > 50%, hardness according to Shore A > 30.

Description of invention

Panel for use in construction industry solves the above presented technical problem by the help of surprising technical effect in that, inter alia, the frame is sealed with a sealant based on silicone or polysulfide. The thermal conductivity of the adhesive/sealant is less than 0.30 W/mK, preferably less than 0.25 W/mK. Furthermore, the adhesive/sealant contains organic and/or mineral hollow microspheres.

Adhesive/sealant according to invention was made based on polysulfide or silicone and/or their derivatives, and includes hollow mineral and/or organic microspheres and other fillers enabling achieving lower thermal conductivity of the material.

The invention will be additionally described based on research description and embodiments.

It was found that the thermal conductivity of the adhesive/sealant below 0.30 W/mK one observes significant improvement in thermal resistance of the frame of IGU or GFP. By further reduction of thermal conductivity of the sealing mass the thermal resistance of the frame of IGU or GFP improves, however to achieve the desired mechanical properties of the sealant and the economics of the product optimal thermal conductivity of the sealant should be around 0.25 W/mK.

Reduced thermal conductivity of the adhesive/sealant is achieved with minimum technical effort if the adhesive/sealant fillers are replaced in part with mineral and or organic hollow microspheres or if these microspheres are added to the adhesive/sealant mass.

Hollow microspheres are expanded closed cell structures or hollow spherical fillers or ovoid shapes ranging in size from 5 to 500 micrometers. Hollow microspheres can also be filled with gas (eg C02, Ar). Hollow microspheres can be based on minerals (glass, ceramics) or based on organic polymers (PE, PU, PS, PMMA). Examples of suitable mineral hollow microspheres are: Eurocell of Europerla, E-spheres of Envirospheres. Example of suitable organic hollow microspheres is Expancel from Akzo Nobel.

The minimum size of mineral hollow microspheres available on the market is 5 μιη while maximum size is up to 500 μπι. The minimum size of the organic hollow microspheres available on the market is 10 μιη, and maximum size up to 1000 μ^ηι. In our case it is not desirable that the mixture would be dominated by the smallest mineral and organic hollow microspheres because their thermal conductivity is significantly higher given the large microspheres. However one must recognize the limits of the maximum size of the microspheres which is subject to technical limitations of the processing equipment. Two component adhesives/sealants are commonly used in IGUs and GFPs for fixing the metal frame between two boards and preventing the escape of the gas from the insulating core. Two component adhesive/sealant offer substantially better vapor and gas barrier compared to those with one component adhesive/sealants. Fillers that are built into the two component adhesive/sealant should not exceed the size of 500 μιη as this could lead to a clogged or malfunctioning of processing equipment. An even greater problem is the abrasion damage to the metering and mixing systems which are emphasized with increase of size and number of solid particles. Additional problem with mineral hollow microspheres is their fragility as they may crush at too high pressures and high mixing velocity.

The research showed that suitable size for the hollow microspheres is around 300 micrometers. Layer thickness of a secondary seal for IGU and GFP is up to 4 mm. It was empirically determined that the particles must be at least 10 times smaller than the thickness of the layer to achieve the even appearance of secondary seal. If there is a requirement for a smoother appearance of the secondary seal one should use even smaller microspheres under 150 micrometers or even less than 100 micrometers.

Particles size - microspheres and fillers - have effect on the mechanical and thermal properties of adhesives/sealants. The larger the particles, the bigger the brittleness of adhesive/sealant. This is due to the increase of the notch effect at each particle. However, larger the hollow microspheres, lower the thermal conductivity of the mass, as the hollow microspheres have significantly lower thermal conductivity (<0.062 W/mK) as the conventional adhesive/sealant (> 0.35 W/mK) which is commonly used as a secondary seal of IGUs and GFPs.

Just the opposite is true for the full fillers such as calcium carbonate (calcite, chalk), calcium sulphate (gypsum), clay, mica, and others. The reason the use of fillers in sealants is the price because adding them significantly reduces the price of adhesive/sealant. Adhesive/sealant without fillers becomes commercially unattractive due to the high price. At the same time with the addition of fillers one achieves the desired tensile modulus. It means that with the combination of different kind of fillers one can obtain the desired hardness, tensile strength, adhesion and viscosity which should be met by the adhesive/sealant to be used in the IGUs and GFPs. Usually secondary sealants for IGUs and GFPs contains 35-50 wt. % of liquid component and 50-65 wt. % fillers, mostly CaC0₃ which may be ground (GCC) or has been treated and precipitated (PCC). Due to the crystal structure and shape the calcium carbonate may have thermal conductivity of 2.4 to 9 W/mK. The larger the particles and quantity of calcium carbonate in the adhesive/sealing mass, the higher its thermal conductivity. The PCC filler loadings in adhesive/sealant formulation typically range from 5 to 15 wt. %, and GCC filler loadings range from 50 to 60 wt. %. In this invention the hollow microspheres were used as a substitute for the filler resulting in significant change of ratio of other fillers, especially CaC0₃ to achieve the desired mechanical properties.

The research has shown that the thermal conductivity of the adhesive/sealants can be reduced under 0.30 W/mK if at least 5 volumetric percent of conventional fillers in the adhesive/sealing mass are replaced with hollow microspheres. This has of course broken down the standard mass ratio of liquid and solid components in the adhesive/sealing mass as the hollow microspheres have significantly lower density and significantly higher specific surface area making it necessary to use more liquid components, in particular polymer for the hollow microspheres to be mixed into adhesive/sealant.

Increasing the proportion of hollow microspheres in the adhesive/sealing mass results in increased brittleness, i.e. its elasticity is decreased while its viscosity and tixotropy is increased significantly. To achieve the target properties of the adhesive/sealant according to the standards and purpose of use it is necessary to increase the proportion of the polymer and even more so proportion of additives to increase elasticity. But even here there is quantity limit as additives for elasticity reduce the adhesion of adhesive/sealant onto metals, glass, plastic spacers and the plasterboard.

The research further showed that the upper limit of hollow microspheres is around 60 vol. % relative to the total sealant volume. At this value the adhesive/sealant mass at the beginning of curing process is barely flowing, and when it has cured it meets the conditions required by standards in the area of IGUs and GFPs.

However, from the viewpoint of the treatment of material, price, and response to fire, there exist an optimal volume proportion of organic and mineral microspheres incorporated in the adhesive/sealing mass. As mentioned earlier, by increasing the quantity of hollow microspheres the viscosity increases which requires more powerful processing equipment for mixing and pumping, while also increasing the proportion of polymer and additives for elasticity contributing significantly to raising the price of the final product. From the standpoint of fire only organic microspheres are critical as they contribute to the combustion enthalpy of the adhesive/sealant, while mineral microspheres reduce the combustion enthalpy of the adhesive/sealant. In our study we have defined that the optimal quantity of organic hollow microspheres is between 20 and 40 vol. % of the total adhesive/sealant volume while the optimal quantity of hollow mineral microspheres is between 10 and 30 vol. % of the total adhesive/sealant volume. δ

In these bounds required mechanical properties of the adhesive/sealant and thermal conductivity under 0.25 W/mK are easily achieved.

Organic and mineral microspheres can also be used together in adhesive/sealant according to this invention. The advantage of organic microspheres is that they contribute to lower thermal conductivity more than inorganic microspheres and are less sensitive to the mixing system. The advantage of mineral microspheres is to lower the enthalpy of combustion. The volume ratio of both types of microspheres together in the adhesive/sealing mass retain similar as to the volume ratio of single type of microspheres.

For particular purposes such as for example high-rise buildings one requires adhesive/sealant which does not spread fire or is self-extinguishing. The thermal conductivity is important in these applications as well, and is achieved similarly as described earlier. The self-extinguishing properties of the mass is achieved by additives reducing the combustion enthalpy such as Al(OH)₃ and Mg(OH)₂ and additives suppressing the fire in gas phase: halogenated compounds (e.g. Saytex 8010, Albemarle) and antimony oxides, and substances that form an inert layer: ammonium polyphosphate, melamine and polyol (eg dipentaeritriol).

Embodiments (Examples of practicing of invention)

Example 1:

We prepared two component adhesive/sealant based on polysulfide. Composition of component A according to weight and volume percent is given in Table 1.

Table 1 :

Isostearic acid (Samson Kamnik) 0.03 0.05

Calcium carbonate (Omya) 61.91 40.64

The materials of Table 1 were mixed at room temperature in planetary mixer DREIS 1L at 60 rpm. First, the liquid components were mixed (3 to 5 min), and later calcium carbonate was added in portions from finest granulation to the largest. After all the fillers were mixed into the mixture, the vacuum mixing was performed for additional 20 minutes.

Separately, the composition of component B according to Table 2 was prepared.

Table 2:

The materials for the preparation of component B were mixed by a laboratory mixer SPEED MIXER FVZ 400 at 2000 rpms 2-times for 30 seconds. Between the two mixing the mass was also hand mixed.

100 parts by weight of component A (Table 1) and 9 parts by weight of component B (Table 2) were mixed to get a homogeneous mixture which was suitable for the preparation of test specimens for mechanical tests and measurement of thermal conductivity. We waited 168 hours for a mixture to completely harden (in accordance with the standards) then performed the tests. The results are summarized in Table 6.

Example 2: We prepared two component adhesive/sealant based on polysulfide mixed with mineral hollow microspheres. Composition of component A according to weight and volume fraction is given in Table 3.

Table 3:

The materials of Table 3 were mixed at room temperature in planetary mixer DREIS 1L at 60 rpm. First, the liquid components were mixed (3 to 5 min), and later calcium carbonate was added in portions from finest granulation to the largest. After all the fillers were mixed into the mixture, the vacuum mixing was performed for additional 20 minutes. At the end microspheres Eurocell 140-23 were added. They were mixed into the mixture for 1 minute and vacuum mixed for another 5 minutes.

The resulting homogeneous mass was hardened with component B which was prepared according to procedure described in Example 1 (Table 2).

100 parts by weight of component A (Table 3) and 16 parts by weight of component B (Table 2) were mixed to get a homogeneous mixture which was suitable for the preparation of test specimens used for mechanical tests and measurement of thermal conductivity. We waited 168 hours for a mixture to completely harden (in accordance with the standards) then performed the tests. The results are summarized in Table 6.

Example 3: We prepared two component adhesive/sealant based on polysulfide mixed with organic hollow microspheres. Composition of component A according to weight and volume percent is given in Table 4.

Table 4:

The materials as given in Table 4 were mixed at room temperature in planetary mixer DREIS 1L at 60 rpm. First, the liquid components were mixed (3 to 5 min). As the first filler Expancel 461 DET 40 d25 was mixed into the mixture, and then calcium carbonate was added in portions from finest granulation to the largest. After all the fillers were mixed into the mixture, the vacuum mixing was performed for additional 20 minutes.

100 parts by weight of component A (Table 4) and 13 parts by weight of component B (Table 2) were mixed to get a homogeneous mixture which was suitable for the preparation of test specimens for mechanical tests and measurement of thermal conductivity. We waited 168 hours for a mixture to completely harden (in accordance with the standards) then performed the tests. The results are summarized in Table 6.

Example 4: We prepared two component adhesive/sealant based on polysulfide mixed with organic and mineral hollow microspheres. Composition of component A according to weight and volume percent is given in Table 5.

Table 5:

The materials as given in Table 4 were mixed at room temperature in planetary mixer DREIS 1L at 60 rpm. First, the liquid components were mixed (3 to 5 min). As the first filler Expancel 461 DET 40 d25 was mixed into the mixture, and then calcium carbonate was added in portions from finest granulation to the largest. After all the fillers were mixed into the mixture, the vacuum mixing was performed for additional 20 minutes. At the end microspheres Eurocell 140-23 were added. They were added into the mixture in 1 minute and further vacuum mixed for another 5 minutes.

100 parts by weight of component A (Table 5) and 15 parts by weight of component B (Table 2) were mixed to get a homogeneous mixture which was suitable for the preparation of test specimens for mechanical tests and measurement of thermal conductivity. We waited 168 hours for a mixture to completely harden (in accordance with the standards) then performed the tests. The results are summarized in Table 6. Table 6:

Example Example Example Example 1 2 3 4

Tensile strength (SIST EN 28339) [MPa] 1.0 0.9 0.6 0.8

Hardness Shore A (ISO 868) 55 50 34 49

Elongation at break (SIST EN 28339) [%] 110.5 105.6 67.7 92.5

Resistance to flow (SIST EN 27390) [mm] 0 mm 0 mm 0 mm 0 mm

Test of constant load (SIST EN 1279-6) 60 28 / 18

[min]

Thermal conductivity [W/mK] 0.40 0.25 0.20 0.23

Claims

PATENT CLAIMS

1. Adhesive/sealant preferably used for construction panel which is sealed along the frame with adhesive/sealant mass, characterized in that an adhesive/sealant mass is based on polysulfide or silicon, further, that the thermal conductivity of said adhesive/sealant mass is less than 0.30 W/mK, preferably less than 0.25 W/mK, and further that adhesive/sealant mass comprises organic and/or mineral hollow microspheres.

2. Adhesive/sealant according to claim 1, characterized in that the adhesive/sealant mass comprises hollow microspheres based on organic polymers in size of 10 - 300 μ^ηι, preferably 10 - 150 μηι, even more preferably 10 - 100 μηι.

3. Adhesive/sealant according to claim 1, characterized in that the adhesive/sealant mass comprises 5 vol. % to 60 vol. %, preferably between 20 vol. % to 40 vol. % hollow microspheres relative to whole adhesive/sealant volume.

4. Adhesive/sealant according to claim 1, characterized in that the adhesive/sealant mass comprises mineral hollow microspheres in size of 5 - 300 μη , preferably 5 - 150 μηι, even more preferably 5 - 100 μιη.

5. Adhesive/sealant according to claim 4, characterized in that the adhesive/sealant mass comprises 5 vol. % to 60 vol. %, preferably between 10 vol. % to 30 vol. % hollow microspheres relative to whole adhesive/sealant volume.

6. Adhesive/sealant according to claim 1 , characterized in that the adhesive/sealant mass comprises hollow microspheres based on organic polymers and mineral polymers.

7. Adhesive/sealant according to claim 6, characterized in that the adhesive/sealant mass comprises hollow microspheres based on organic polymers in size of 10 - 300 μιη, preferably 10 - 150 μηι, even more preferably 10 - 100 μ^ηι, and mineral hollow microspheres in size of 5 - 300 μηι, preferably 5 - 150 μιη, even more preferably 5 - 100 μπι.

8. Adhesive/sealant according to claim 6, characterized in that the adhesive/sealant mass comprises 5 vol. % to 60 vol. %, hollow mineral and organic microspheres relative to whole adhesive/sealant volume.

9. Adhesive/sealant according to any previous claims, characterized in that it comprises additives for self extinguishing of fire.

10. Adhesive/sealant according to any previous claims, characterized in that the additives for self extinguishing of fire are chosen from inorganic hydroxides such as Al(OH)₃ and Mg(OH)₂, additives suppressing the fire in gas phase such as halogenated compounds and antimony oxides, and substances that form an inert layer: ammonium polyphosphates, melamines and polyols.